groupElems :: Eq a => [a] -> [[a]]
groupElems [] = []
groupElems xs = groupElemsHelper xs [] []
  where
    groupElemsHelper [x] curlist res
      | null curlist = reverse ([x] : res)
      | x == last curlist = reverse (curlist : res)
      | otherwise = reverse ([x] : res)
    groupElemsHelper (prev:xs) curlist res
      | null curlist = groupElemsHelper (prev:xs) (prev : curlist) res
      | head xs == prev = groupElemsHelper xs (head xs : curlist) res
      | otherwise = groupElemsHelper xs [] (curlist : res)